Technical Field
Certain embodiments of the present invention relate to cryocoolers and cryocooler operation methods that give rise to coldness by expanding high-pressure helium supplied from a compression device.
Description of Related Art
Examples of prior-disclosed cryocoolers include displacer-type cryocoolers furnished with an expander configured to movably accommodate a displacer in the interior of a cylinder. With displacer-type cryocoolers, while the displacer in the cylinder interior is reciprocated, helium inside the expander is made to expand, giving rise to coldness. The helium chilling that occurs in the expander builds up in a regenerator and meanwhile is transmitted to a cooling stage, which, reaching a desired cryogenic temperature, refrigerates a refrigeration article connected to the cooling stage.
When a cryocooler is used to generate liquid helium under, for example, atmospheric pressure, it develops coldness at a usual 4 K level. If the temperature that the chill reaches could be lowered further, helium superfluid transition temperatures, for example, could then be made available.